System Engineering (SE) is becoming increasingly knowledge intensive. Knowledge Management is recognized as a crucial enabler for continuous process improvement in engineering projects. Particularly, capitalization and sharing, of knowledge resulting from experience feedback are valuable asset for SE companies. In this paper, we focus on the formalization of engineering experience aiming at transforming information or understanding gained by projects into explicit knowledge. A generic SE ontological framework acts as a semantic foundation for experience capitalization and reuse. This framework is operationalized with Conceptual Graphs formalism and applied to a transport system engineering use case.